Fix GitHub actions

Follow-up to #630.
The check for the target git sha can does not work in the molecule step.
Instead expose the sha through an env variable in GitHub actions.

ansible/molecule/default/converge.yml

@@ -2,15 +2,9 @@
 - name: update previous release to newest release
   hosts: all
   tasks:
-    - name: install git dependency
-      apt:
-        pkg: git
-    - name: obtain latest git hash in current tree
-      command: git rev-parse HEAD
-      register: git_hash
     - name: set current github commit as version when available
       set_fact:
-        paperlessng_version: "{{ git_hash.stdout }}"
+        paperlessng_version: "{{ lookup('env', 'TARGET_GITHUB_SHA') | default('master', True) }}"
     - name: update to newest paperless-ng release
       include_role:
         name: ansible